Photographic films and papers are regularly handled in long rolls. The length of the roll may be as short as several inches, or, in the case of high volume commercial photography, several hundred feet. The processing of such long rolls of materials requires attention to cost, speed, product safety, simplicity and reliability.
A variety of pieces of commercial photographic processing equipment are equipped with film or paper transport mechanisms. This equipment includes, but is not limited to: printers, developers, punches, editors, negative baggers and print baggers. Typically, photographic equipment which processes long rolls of film or paper operates in an automated or semi-automated manner. In this fashion, the equipment processes, sequentially, a series of photographic exposures with minimal operator intervention. By way of example, a spool of developed photographic film may be placed in an automated photographic printer which locates the optical center of each individual negative on the long roll, applies exposure correction factors, exposes one section of a long roll of photographic paper from said negative, and advances the film roll to the next exposure. This entire cycle may take less than one second. In this interval, both the photographic negative material and the photographic paper must be accelerated, decelerated and fixed in precise position and correlation.
Problems occur in transporting both long roll paper and negative in this environment. Placement of the materials on the optical center of the equipment is critical. Present centering methods require the use of a pair of movable retaining collars on a rotating shaft. These retaining collars serve to capture the long roll material at the edges, guiding the material between the collars. However, most commercial photographic processing equipment utilizes several such shaft/collar guide combinations, which establish a three dimensional path over which the long roll material travels.
Accordingly, the physical location of each pair of retaining collars on each guide shaft must correspond precisely to each pair of collars on every other shaft. Further, the position of each pair of retaining collars on each shaft must correspond precisely to the physical dimension of the material being transported. Finally, the position of the retaining collars must be set to insure positioning of the film or paper in precise relationship to the optical center of the photographic processing equipment. The set up of the existing shaft/collar combinations is, accordingly, time-consuming and fraught with error.
Moreover, the existing guides have a tendency to damage film edges. The collars presently known feature a bearing surface for the material edge that is essentially perpendicular to the material transported. Film and photographic paper edges are relatively fragile, and are often notched or punched for identification purposes, which serves to further weaken the edge. When long roll material fails (particularly film negatives), it is common for the long roll material to split along the longitudinal axis of the long roll material, creating a tear that may extend across several individual frames or exposures. Protection of the material edge is, therefore, of paramount interest during transport.
The operations of threading, and guiding at high speed, often result in misalignment of the transported material in relation to the guide shaft/collar combination. The material may tend to "climb" the edge of the collar, thereby disengaging the long roll material from the guide path. In an automated environment, the material drive mechanism may continue to operate, resulting in continuous feeding of disengaged long roll material, which results in certain damage to the transported material, and frequent damage to the material transport mechanism. This tendency to climb is most pronounced when the material is spliced. Then stiffness of the transported material is usually reduced at the splice, whereas the tension on the long roll material remains constant during transport. Under these conditions, the spliced section of the material buckles toward the longitudinal center of the material. In this configuration, the material edge presents a reduced edge dimension to the guide collar surface, facilitating the tendency of the material to climb out of the space between the guide collars.
The present invention is an improved spindle mechanism to replace the paired collars on each shaft, which overcomes the many shortcomings of the current equipment.